Grinding machine



Jan. 23, 1962 R. H. GEORG ETAL GRINDING MACHINE 2 Sheets-Sheet 1 Filed Sept. 8, 195a INVENTORS 6 4 P/ulz'p E 750,0,0, MM. lanai/M \IIAJ Jan. 23, 1962 R. H. GEORG ETAL 3,017,727

GRINDING MACHINE Filed Sept. 8, 1958 2 Sheets-Sheet 2 BYP z'p ZZZ opp,

I IMO 3,017,727 Patented Jan. 23, 1962 3,017,727 GRINDING MACHINE Raymond H. Georg, 424 E. Edwards St., Springfield, 111., and Philip E. Kopp, Springfield, 111.; said Kopp assignor to said Georg Filed Sept. 8, 1958, Ser. No. 759,461 10 Claims. (C1. 51-96) This invention relates, in general, to grinding machines, and has particular relation to a machine for grinding, honing, or sharpening the scraping, or etching edge of a retouching, or etching knife to predetermined specifications or formula for use in photography and other fields, although, in its broader aspects, the invention is not limited to that particular purpose.

In photography, the negative is subject to alterations and corrections by means of adding tone or removing tone from the developed image. The present invention is concerned, in its photographic application, with the grinding, honing, or sharpening of knives used for the removal of tone, or density, from the developed image. This is accomplished by using a scraping or cutting tool, commonly called an etching or retouching knife, for scraping the emulsion surface of the film. The process is called etching.

Such knives, which are, of course, included within the term workpiece in certain of the broader of the appended claims, take a wide variety of styles and forms and have, heretofore, depended upon hand sharpening on whet stones, strops and the like, for the creation and maintenance of their working edges.

The process of etching is an extremely delicate one. The emulsion of the photographic film is approximately one thousandth of an inch in thickness. The complete range of tone of the developed image formed therein is thus contained within that dimension. These tones are not evenly dispersed from top to bottom but are concentrated at the top of the emulsion where the action of the light and developer has been greater. Some tones do not penetrate the entire thickness but disappear entirely at a point within it. Thus, if a retoucher wishes to remove one-half the tone of a given area, he will have to remove less than one-half of the emulsions thickness, if onetenth of the tone, less than one-tenth of the thickness of the emulsion.

From the foregoing it will be apparent that the emulsion must be removed in exceedingly thin, actually microscopically fine layers to make subtle alterations in tone. It will also be apparent that the tool with which this work is done must possess an edge which is free from imperfections to a degree that is almost microscopic, in

order that the tone will be even, Well blended with adjacent tones and without scratches, gouges or other flaws.

All hand sharpened knives, by their very nature, have irregularities of edge, both in smoothness and contour, which are imparted to the emulsion surface, resulting in uneven, scratchy and gouged tones which must be repaired with pencil work before they are at all usable. As a result etching has heretofore been an extremely difficult and generally unsatisfactory process requiring great skill and consuming much time, especially in endeavoring to maintain the working edge of the knife. The microscopic perfection of edge demanded for the work has been unobtainable by hand sharpening.

One of the main objects of the present invention is to provide a grinding (which term includes honing, sharpening, or the like) machine for automatically generating, by grinding, a cutting or scrapping edge, which may be microscopically flawless, on an etching or retouching blade in accordance with a predetermined and fixed specification, or formula, which experience has proven to be the most nearly perfect for the work the blade is intended to do, eliminating the need for hand sharpening of such knives and thus providing means by which anyone, even the most inexperienced, may create and maintain a superior working edge on such knives.

Another object is to provide a mechanical grinder, or sharpening machine of exceedingly simple construction and operation, and which will automatically generate a cutting or scraping edge possessing an arcuate contour of predetermined and fixed radius, a predetermined and fixed, within usable limits, cutting, or sharpness angle, and a predetermined and fixed working angle, all congruently and simultaneously.

Another object is to provide a grinding machine having a grinding wheel rotatable about its axis and provided with a peripheral grinding surface, a blade or Work holding member disposed generally radially with respect to the axis of the wheel and having a workpiece supporting end positioned toward the wheel, a pivot which pivots the Work holding member for oscillation of its work supporting end transversely of the peripheral grinding surface, means for attaching a blade, or workpiece to the work supporting end of the work holding member for movement transversely of the peripheral grinding surface and in contact therewith during oscillation of the work holding member, and means for urging both the work holding member and the pivot yieldingly toward the peripheral grinding surface whereby to press the workpiece against the peripheral grinding surface and to maintain a fixed radius of the workpiece with respect to the pivot regardless of wear of the peripheral grinding surface.

Another object is to provide a gauge on the work holding member movable to loading position where the workpiece may be placed against the same in attaching it to the work supporting end to assure positioning of the workpiece at a fixed radius with respect to the pivot and wherein the gauge is movable to running position clear of the portion of the workpiece which contacts the pe ripheral grinding surface.

Another object is to provide a guide for guiding the oscillating movement of the work holding member in a true path transversely of the peripheral grinding surface of the grinding wheel; also an abutment on the work holding member engageable with the guide for preventing contact of the workpiece with the peripheral grinding surface after the latter has worn to a predetermined minimum diameter less than which the scraping edge or sharpness angle of the edge of the workpiece would be beyond usable limits.

Further objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, it being understood that the invention is limited only within the scope of the appended claims and not to the particular embodiments selected for illustration.

In the drawings:

FIGURE 1 is a perspective view of a grinding machine embodying the present invention;

FIGURE 2 is a top plan view of the knife bar or work holding assembly;

FIGURE 3 is an outer side view of the knife bar assembly as shown in FIGURE 2;

FIGURE 4 is a fragmentary view showing the gauge in running position and the scraping or etching edge of the knife blade in contact with the periphery of the grinding wheel;

FIGURE 5 is a side view of the blade;

FIGURE 6 is a longitudinal sectional view through the blade taken on the line 6-6 of FIGURE 5;

FIGURE 7 is a fragmentary sectional view taken on the line 7-7 of FIGURE 1 through the bell crank as sembly for oscillating the knife bar; and

FIGURE 8 is a fragmentary sectional view taken on 3 the line 8-8 of FIGURE 1 through the gear and crank assembly for actuating the bell crank assembly shown in FIGURE 7.

Referring now to the drawings, the frame 1 is open or hollow from the bottom and has at one end an upright hollow portion 2 in which is mounted an electric motor 3. A spindle 4, journaled at 5 in the frame 1, is rotatable upon its axis by the motor 3 and has a grinding, honing or sharpening wheel 6 fixed thereon for rotation with the spindle 4.

The grinding wheel 6 is formed of suitable abrasive material and has a concave peripheral grinding surface 7. By using the concave peripheral surface 7 of curved or areuate form, as shown, there is no point of tangency between the wheel and the blade edge as the blade is oscillated transversely of the peripheral grinding surface as will hereinafter appear. Thus, if the blade dwells momentarily at each end of the oscillation, as it does, it does not grind a fiat spot at that point because contact is made with the wheel along the entire length of the edge, and, accordingly, pressure is equal along the entire length of the blade edge.

If the periphery of the wheel were flat a curvature could be ground upon the blade by using a fixed instead of a movable pivot point. areuate grinding systems and it requires an adjusting mechanism to bring the blade into contact with the wheel.

As shown in FIGURES 5 and 6, the blade 8 is in the form of a thin flat strip of steel, or other suitable material, with one end and the edges of right angle form at one end at 9 and having one surface tapered at 10 to the scraping or etching edge 11 which is of curved, or areuate form, as shown. The scraping or etching edge 11 is ground at an angle (FIGURE 6) to form the cutting or sharpness angle. This is accomplished by contacting the edge 11 of the blade with the peripheral grinding surface 7 above the center or axis of the wheel 6.

The blade is used with a knife handle in which is secured a collet having a slot for receiving the blade and with a ferrule coacting with the collet for clamping the blade therein. The knife with the handle and the provisions for mounting the blade thereon form no part of the present invention, and, therefore, are not illustrated or described in the present application.

Returning now to the grinding machine, a blade or work holding bar assembly 12 is disposed generally radially with respect to the axis of the wheel 6 and comprises a blade holding bar 13 having a blade supporting end presented toward the wheel 6 and a guide member 14 having a slot 15 in which the outer end of the bar 13 is pivoted on a pivot pin 16 for oscillation transversely of the peripheral grinding surface 7.

In loading the blade onto the bar 13 or applying the same thereto, the blade is positioned on the bar 13 between a pair of upright guide pins 17 carried by the bar 13 and a clamping screw is screwed into the bar 13 and having a shoulder at 19 for clamping the blade firmly in place on the bar.

The guide member 14 has axial sliding movement in a cylindrical chamber 20 at right angles to the axis of the wheel 6 in an upright portion 21 on an angular leg 22 of the frame 1. An expansile spring 23 interposed between the adjacent end of the inwardly opening tubular end of the guide member 14 and the end wall 24 of the chamber 20 urges both the bar 13 and the pivot pin 16 yieldingly toward the peripheral grinding surface 7. The scraping or etching edge 11 of the blade 8 is thus pressed yieldingly against the grinding surface 7, as shown in FIGURE 4, and the accompanying movement of the pivot pin 16 maintaints a fixed radius x (FIGURE 2) of the blade edge 11 with respect to the pivot pin 16 regardless of wear of the peripheral grinding surface 7.

A gauge member 26 is pivoted on the bottom of the bar 13 by a pivot pin 27. The gauge member 26 has on one arm 28 thereof a first upstanding abutment 29 That is what is done in most and a second upstanding abutment 30. The abutment 30 coacts with the bar 13 at 31 to limit clockwise pivotal movement of the abutment 29 (FIGURES l and 2) to the position shown in FIGURE 2. In this position, which is loading position, as the blade 8 is placed on the bar 13 its scraping or etching edge 11 is positioned against the abutment 29, thus, assuring the fixed radius x of said blade edge 11 with respect to the pivot pin 16 in attaching the blade to the bar 13.

To provide clearance between the blade supporting end of the bar 13 and the grinding wheel 6 so that the gauge member 26 may be swung to the position shown in FIGURES 2 and 4 for accurately gauging the position of the blade 8 in attaching same to the bar 13, the upstanding end of the pivot pin 16 and the back end 24 of the upright portion 21 of the frame 1 are squeezed, for example, between the thumb and finger. This presses the blade holding bar assembly 12 to the right (FIGURES 2 and 4) and away from the periphery of the wheel 6 to permit movement of the abutment 29 to the position shown in FIGURE 2 in loading the machine.

The other arm 32 of the gauge member 26 coacts with a depending pin 33 carried by the blade arm 13 to limit counterclockwise movement of gauge 26 to running position, as shown in FIGURE 4.

The function of the gauge is two-fold. First, it positions the knife blade 3 at a fixed distance from the pivot 16, each time the blade 8 is inserted into the machine for sharpening. As a result, the radius upon which the contour is ground in the sharpening action remains constant. While each sharpening shortens this radius by the amount of metal removed, this amount is almost immeasurable and has no practical effect upon the usefulness of the knife. Also, since the next time the blade is sharpened, it is again positioned against the gauge abutment 29, and a similar amount of metal removed for that sharpening, the radius of the contour is within a few millionths of an inch of every other sharpening, almost mathematically identical.

Secondly, the gauge positions the knife so that the dressed, areuate surface of the grinding wheel coincides With the ground, areuate surface of the cutting edge of the blade, each time the blade is inserted in the machine for grinding.

As distinguished from the provision of the present invention for assuring accurate positioning of the blade edge 11 at a fixed distance from the pivot 16, if the blade were inserted in a different position as to distance of its edge 11 from the pivot pin 16, it would contact the grinding surface 7 either on the toe of the blade, or on the heel of the blade, depending upon whether it protruded too far or too little from its correct and accurate positioning. In such case, in grinding the blade edge 11 a new are would be generated, the chord of which would be at variance with the chord of the previously generated arc.

If, with the blade in such a different position, the grinding operation were continued long enough, the new arc would eventually remove and replace the old one. But, since a small amount of metal is being removed at a given time, the time required to do this would be prohibitive. The operator, accustomed to an average grinding time of thirty to forty-five seconds would remove the blade to find that the blade possessed two arcs, instead of one.

Where such two arcs intersected there would be, in effect, a high spot, or point, and pressure per square inch at this point would be increased so much that as the blade is stroked across the film, it would dig much deeper than intended and result in a ruined negative.

Moreover, if the blade were repeatedly placed in varying positions a series of arcs would be formed, and where each arc intersected the other, there would be high spots, and the blade would be totally unusable.

Therefore, the provision for assuring a fixed distance between the blade edge 11 and the pivot pin 16 is an important aspect of the present invention. The provision for movement of the pivot pin 16 along with the blade edge 11, toward the grinding surface 7 upon wear of the grinding surface whereby to maintain a fixed radius of the edge 11 with respect to the pivot pin 16, without adjustment, and regardless of wear of the peripheral grinding surface 7, is also highly important.

For the purpose of oscillating the blade arm 13 and the blade carried thereby transversely of the peripheral grinding surface 7 and at a rate in relation to the rotation of the grinding wheel, a driving connection is provided between the spindle 4 and a vertical pin or shaft 35 journaled for rotation in bearings 36 in the adjacent portion of the frame 1. The driving connection comprises, for example, a worm or screw 37 fixed to rotate with the spindle 4 and meshing with a worm gear 38 fixed on the shaft 35 to rotate the same therewith.

The upper end of the shaft 35 has an integral upstanding and eccentrically disposed crank pin 39. The pin 39 is headed at its upper end at 40 and carries a crank roller sleeve 41. The roller 41 coacts with a bell crank member 42 pivoted upon a vertical pin or shaft 43 carried by the frame 1. The member 42 carries a depending pin 44 having thereon a roller sleeve 45 which coacts with the adjacent edge of the knife bar 13.

A spring 48 connected at one end (FIGURE 2) to a pin 49 projecting from the adjacent portion of the frame 1 and connected at its opposite end to a pin 55) carried by and depending from the bar 13 maintains the bar 13 yieldingly against the roller sleeve 45. v

The electric motor 3 is provided with flexible conductors 52 having a pronged or other suitable quick detachable connector plug 53 for application to an electric out let, as well understood in the art. A push-button, or other suitable switch 54 on the frame 1 enables energizing and deenergizing the motor 3 and thereby starting and stopping of the rotation of the spindle 4.

With the switch 54 closed, the motor 3 is energized and rotates the spindle 4 and the grinding wheel 6 thereon. The rotation of the spindle 4 also rotates the shaft 35 at a fixed rate in relation to the rotation of the grinding wheel 6 through the worm 37 and meshing gear 38. R0- tation of the shaft 35 causes, through the eccentric roller 41 and in conjunction with the spring 48, oscillation of the blade 8 on the arm 13 transversely of the grinding surface 7 to grind the edge 11 of the blade 8 in the manner previously described, the blade edge 11 being maintained yieldingly in contact with the grinding surface 7 by the spring 23.

A guide pin 56 fixed in the frame l at 57 (FIGURE 2) projects beneath the arm 13 and by cooperation therewith guides the oscillating movement of this arm in a true path transversely of the peripheral grinding surface 7. A gauge spacer ring 58 on the pivot pin 27 for the gauge member 26 spaces the gauge member from the bottom of the bar 13 and acts as an abutment engageable with the guide pin 56 for preventing contact of the blades edge 11 with the peripheral grinding surface after the latter has worn to a predetermined minimum diameter less than which the sharpness angle of the edge 11 of the blade would be beyond usable limits.

The embodiment of the invention shown in the drawings is for illustrative purposes only and it is to be expressly understood that said drawings and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

We claim:

1. A grinding machine comprising, in combination, a frame, a spindle journaled for rotation in said frame, a grinding wheel fixed on said spindle for rotation therewith and having a peripheral grinding surface, a guide member having rectilineal sliding movement in a chamber in a portion of said frame at right angles to the axis of said grinding wheel, a non-rotatable flat blade holding bar pivoted in a slot in said guide member on a pivot pin for oscillation transversely of the peripheral grinding surface, a spring urging said blade holding bar, said pivot pin and said guide member toward said peripheral grinding surface, a shaft jO lllllaiied for rotation in said frame, a driving connection between said spindle and said shaft, a crank pin on said shaft, a crank roller sleeve on said pin, a pivoted bell crank member having a pin on which is a second roller sleeve coacting with an adjacent edge of said blade holding bar, and a spring connected between said frame and said blade holding bar and acting yieldingly to maintain said edge of said blade holding bar against said second roller sleeve for oscillation of said blade holding bar about its pivot under the action imparted to said bell crank member by said crank roller sleeve on said crank pin.

2. A grinding machine according to claim 1 wherein there is a gauge on said work holding member movable to loading position where the workpiece may be placed against the same in attaching the workpiece to said work supporting end to assure positioning of said workpiece at a fixed radius with respect to said pivot pin, said gauge being movable to running position clear of the portion of the workpiece which contacts said peripheral grinding surface.

3. A grinding machine according to claim 1 wherein there is a gauge member having an abutment and pivoted to said work holding member to permit swinging said abutment into loading position in proximity to the work supporting end of said work holding member for placement of the workpiece against said abutment to assure a fixed radius of said workpiece in attaching same to said work holding member, said gauge member having pivotal movement in the opposite direction to running position clear of the portion of the workpiece which contacts said peripheral grinding surface.

4. A grinding machine according to claim 1 wherein there is a gauge member having a first abutment and pivoted to said Work holding member to permit swinging said abutment into loading position in proximity to the work suppolting end of said work holding member for placement of the workpiece against said abutment to assure a fixed radius of said workpiece in attaching same to said work holding member, said gaiuge member having pivotal movement in the opposite direction to running position clear of the portion of the workpiece which contacts said peripheral grinding surface, and a second abutment on said gauge member for coaction with said work holding member to stop said first abutment in predetermined loading position.

5. A grinding machine according to claim 1 wherein the grinding wheel is mounted on a spindle rotatable upon its axis by an electric motor, and gear and crank means driven by said spindle and coacting with said work holding member for oscillating the same at a fixed rate in relation to the rotation of said grinding wheel.

6. A grinding machine according to claim 1 wherein there are guide pins on said work holding member between which and a clamping screw the work is adapted to be positioned and clamped to said work holding member.

7. A grinding machine according to claim 1 wherein there is a guide for guiding the oscillating movement of the work holding member in a true path transversely of the peripheral grinding surface of the grinding wheel.

8. A grinding machine according to claim 1 wherein there is a guide for guiding the oscillating movement of the work holding member in a true path transversely of the peripheral grinding surface of the grinding wheel, and an abutment on said work holding member engageable with said guide for preventing contact of the workpiece With the peripheral grinding surface after the latter has worn to a predetermined minimum diameter less than which the scraping edge or sharpness angle of said edge of the workpiece would be beyond usable limits.

9. A grinding machine according to claim 1 wherein the axis of said spindle is disposed at right angles to the axis of said rectilinearly movabl guide member.

10. A grinding machine according to claim 1, wherein said blade holding bar has a pair of upright guide pins and a clamping screw for positioning and clamping a retouching knife blade in place on said bar for cooperation with said grinding Wheel.

References Qited in the file of this patent UNITED STATES PATENTS Gonard Apr. 16, 1912 B'usler Mar. 14, 1916 Bugbee Oct. 12, 1926 Devine Apr. 12, 1927 Arter Jan. 13, 1942 Barrett Aug. 3, 1943 Fendr-ing June 4, 1946 Erwin et a1. Aug. 5, 1947 Jensch Feb. 12. 1957 

